Trehalose is composed of two glucopyranose molecules linked by an α, α-1,1-glycosidic bond. It is a stable non-reducing disaccharide, with high safety and good stability. It is widely used in the fields of medicine, food, makeup and agriculture, etc. Since 1995, trehalose has been approved as a food additive in Japan, the United States, the European Union, etc. In 2005, trehalose was officially approved as a new resource food by the Ministry of Health of P. R. China.
In 1993, Hayashibara Biochemical Labs first discovered that the maltooligosyl trehalose synthase (MTSase) and maltooligosyl trehalose trehalohydrolase (MTHase) could be used to produce trehalose through the synergistic effect thereof by using liquefied starch as a substrate, and first achieved the industrial production of trehalose. At present, some enterprises in China have started to produce trehalose, but the product performance and yield are still inferior to imported products and the production costs remain high. What is more challenged is that the selling price of trehalose continues to drop to meet the market demands, which bringing great challenge and pressure for the production of trehalose. Therefore, how to increase the yield of trehalose, achieve large-scale production of trehalose at low cost, and provide it to massive common consumers's tables has become a hot issue in the academic and industrial circles.
At present, the industrial production of trehalose is mainly through two methods: (1) using trehalose synthase, and using maltose as a substrate to generate trehalose through intramolecular transglycosylation; (2) using starch liquefaction liquid as a substrate to produce trehalose through the synergistic effect of MTSase and MTHase. The two methods can achieve the similar yield of trehalose. However, considering the production cost and the cycle, it is more convenient and inexpensive to produce trehalose by using starch as a substrate. Therefore, the production of trehalose through the synergistic effect of MTSase and MTHase is more advantageous.
The double enzymatic method used at home and abroad includes medium-low temperature enzyme systems (source strains include Arthrobacter sp. Q36, Arthrobacter ramosus S34, Brevibaterium helvolum, etc.) and high temperature enzyme systems (source strains include Sulfolobus solfataricus KM1 and Sulfolohus acidocaldarius ATCC 33909, etc.). The high temperature enzyme systems usually have a high trehalose conversion rate, and have high thermal stability. They can convert starch to trehalose at a relatively high temperature, and it is not easy to contaminate bacteria during the production process. However, compared with the medium-low temperature enzyme systems, the high-temperature enzyme systems have low protein expression level, which is not conducive to their industrial applications.